“It not only undermines a criminal investigation, in this case a homicide, but it also can, and does, put a witness to a homicide in harm’s way,” Craig told reporters at police headquarters, adding Nevin later removed the postings, which contained unredacted police reports that contained “confidential and sensitive” information about at least two potential witnesses to the crime.

Nevin sent the media a package, which he also reportedly posted on Facebook, that included audio files of police dispatches, and a police report of a shooting that occurred Nov. 23 at Junction and Warren on Detroit’s west side. The report included the first name of a woman who told police about the shooting, along with her phone number and address.

“The Detroit Fire Fighters Association will continue to express professional factual concern publicly over Detroit Police / Fire and EMS mismanagement, manipulation and flat-out misrepresenting public safety response to the public,” Nevin said in the news release.

Craig said releasing that information put the tipster in danger. He didn’t elaborate Thursday on which charges he’d seek, telling reporters that he didn’t want to discuss possible charges. He said his investigators have had several conversations with assistant Wayne County prosecutors and spoke with Wayne County Prosecutor Kym Worthy about the case. The county’s public corruption unit is reviewing the facts.

The Prosecutor’s Office spokeswoman said late Thursday that the office hasn’t “hasn’t been presented” with paperwork about the incident.

Nevin in recent months has been waging a bitter battle with the Fire Department over the implementation of a controversial new response policy that has firefighters responding to some calls on a less emergent basis without lights and sirens.

It’s not clear what, if any, laws might have been broken with Nevin’s postings. At least one legal expert believes posting a potential crime witness’ information online could pose problems.

Since someone could use the personal details to find the witness and their associates, “that’s inviting trouble,” said Brad Shear, a Maryland-based attorney who focuses on social media law related issues.

“… Just the fact this person may have some information that could convict someone puts them or their family in harm’s way,” he said.

Mike Rataj, an attorney representing Nevin, would not address why his client shared posts with unredacted police reports. He said city officials are “trying to silence” Nevin for exercising his “First Amendment right to speak out on behalf of his members.”

Rataj said the Police Department on Wednesday attempted to Mirandize Nevin, but Rataj contacted internal affairs and told them “he’s not making a statement,” he said.

“They are trying to concoct some kind of criminal case against him,” Rataj said. “There’s no crime. To use the criminal process to try to silence somebody who is trying to protect members and let the public know what’s going on, that’s criminal.”

Rataj rather contends that Craig, Fire Commissioner Eric Jones and the Duggan administration are coming down on Nevin for his ongoing criticism of public safety leadership in Detroit that Nevin has argued is “manipulating” and “misrepresenting” response times.

“The chief should be very careful and the mayor should be very careful if they are going to go down that road,” Rataj said. “File that one under: Be careful what you ask for.”

The system, which Jones and Mayor Mike Duggan have defended as “sound policy,” has been the subject of a recent unfair labor charge.

The union in November argued that the policy was “unilaterally imposed” without regard for the bargaining unit or the public. The city’s Law Department has countered the claim is “baseless.”

Jones put the new system in place in August that classifies runs by two codes: one for emergent runs, which uses lights and sirens, and the other for non-emergent calls, which does not.

Jones has argued that disregarding traffic signals and speed limits with the activation of lights and sirens for every single run — even when it’s not urgent — is unnecessarily dangerous.

Jones and his staff have noted the department receives 400 to 500 requests for fire-related incidents per week. About 50 percent, they contend, are non-life-threatening.

During a council committee session last month, the fire administration said the department had 17 firefighter-involved crashes in 2017.

But the union has detailed numerous runs that have been dispatched improperly since the code system went into place and said it fears Jones’ policy could endanger the public and Detroit’s firefighters.

“This data speaks for itself, it is sickening and repeats itself in many forms every day/night in the streets of Detroit,” Nevin said in the release of the unredacted reports to the media. “If Detroit Public Safety personnel is so disorganized and undermanned as to not have the ability to properly back each other in emergency events, what response can the 911 caller expect?”

He called for police, fire and EMS to be restored to “adequate strength to properly protect the city’s 139 square miles, human life depends on it.”

Craig denied Thursday that there was any effort on the part of the Police Department to silence Nevin. Craig also stressed that he alone sought the criminal review of Nevin’s alleged conduct on social media.

“The mayor and Jones were not involved in the decision to launch a criminal investigation. I never consulted the mayor about this; he leaves those decisions up to me. Since I’ve been here, he’s never been involved in any decision about who I investigate,” Craig said.

“This has nothing to do with infringing on his First Amendment rights. Launching this criminal probe had nothing to do with his criticism of this department and its response time to this homicide. However, it had everything to do with the release of information containing confidential and sensitive information relative to several witnesses to a homicide.”

Duggan’s spokesman, John Roach, declined to comment on Rataj’s claims. The fire commissioner could not be immediately reached for comment on Thursday.

Rataj declined further comment after Craig addressed the investigation on Nevin’s social media posts.

Craig noted Nevin asserts that it took the department about 40 minutes to get to the homicide scene in question. But Craig explained that the initial call was put out by dispatchers as an unknown trouble call, which typically isn’t treated as a top priority run.

Firefighters arrived on the scene and determined there was a shooting victim and then contacted dispatch for assistance. Craig said the case remains under investigation but added from the time authorities were alerted that there was a homicide, the response was six minutes. The initial call for unknown trouble, Craig told reporters, “might have been 40 minutes. I’m not certain.”

“If we have a priority one call, and it took us 40 minutes to get to it, I’m not going to deny it,” Craig said. “We’ll investigate, and we did look into this matter, because initially when I heard about it, I was very concerned.”

Rataj said he intends to take action on Nevin’s behalf, but he declined to provide details on what it would be, or when.

“This guy is a dedicated firefighter. He is tough as nails and he’s not afraid of these people,” Rataj said. “He’s not going to play politics with people’s lives.”